From 17af5da98cd2c9ec958421ae2108f877e0945451 Mon Sep 17 00:00:00 2001 From: Alexandre Oliva Date: Wed, 21 Sep 2016 22:01:16 -0300 Subject: [PR19826] fix non-LE TLS in static programs An earlier fix for TLS dropped early initialization of DTV entries for modules using static TLS, leaving it for __tls_get_addr to set them up. That worked on platforms that require the GD access model to be relaxed to LE in the main executable, but it caused a regression on platforms that allow GD in the main executable, particularly in statically-linked programs: they use a custom __tls_get_addr that does not update the DTV, which fails when the DTV early initialization is not performed. In static programs, __libc_setup_tls performs the DTV initialization for the main thread, but the DTV of other threads is set up in _dl_allocate_tls_init, so that's the fix that matters. Restoring the initialization in the remaining functions modified by this patch was just for uniformity. It's not clear that it is ever needed: even on platforms that allow GD in the main executable, the dynamically-linked version of __tls_get_addr would set up the DTV entries, even for static TLS modules, while updating the DTV counter. for ChangeLog [BZ #19826] * elf/dl-tls.c (_dl_allocate_tls_init): Restore DTV early initialization of static TLS entries. * elf/dl-reloc.c (_dl_nothread_init_static_tls): Likewise. * nptl/allocatestack.c (init_one_static_tls): Likewise. --- nptl/allocatestack.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) (limited to 'nptl') diff --git a/nptl/allocatestack.c b/nptl/allocatestack.c index 60b34dc6fc..3016a2ed5c 100644 --- a/nptl/allocatestack.c +++ b/nptl/allocatestack.c @@ -1207,9 +1207,12 @@ init_one_static_tls (struct pthread *curp, struct link_map *map) # error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined" # endif - /* We cannot delay the initialization of the Static TLS area, since - it can be accessed with LE or IE, but since the DTV is only used - by GD and LD, we can delay its update to avoid a race. */ + /* Fill in the DTV slot so that a later LD/GD access will find it. */ + dtv_t *dtv = GET_DTV (TLS_TPADJ (curp)); + dtv[map->l_tls_modid].pointer.to_free = NULL; + dtv[map->l_tls_modid].pointer.val = dest; + + /* Initialize the memory. */ memset (__mempcpy (dest, map->l_tls_initimage, map->l_tls_initimage_size), '\0', map->l_tls_blocksize - map->l_tls_initimage_size); } -- cgit v1.2.3